class_docstr: Use `PruningModifier` to prune the small weight value to 0.
  The pruning is channel-wise. Using the channel-wise L2 norm to represent the degree of sparsity.
  If the L2 norm less than the threshold provided, all the value of this channel will be set to 0.
  
  Supported pruning functions: `Convolution`, `Deconvolution`, `DepthwiseConvolution`, 'DepthwiseDeconvolution', 'Affine'
  
  Examples:
  
  .. code-block:: python
  
     pred = Model(...)
  
     import nnabla.experimental.graph_converters as GC
  
     modifiers = [GC.PruningModifier(pruning_threshold=0.1)]
     gc = GC.GraphConverter(modifiers)
     pred = gc.convert(pred)
code: def modify(self, f, inputs):
      if f.info.type_name not in self._fct_set:
          return
  
      # Prune the weight
      x, w = inputs[:2]
      b = None
      if len(inputs) == 3:
          b = inputs[2]
      output_channel = self.calculate_axis(f)
      shape = list(range(w.ndim))
      shape.pop(output_channel)
      l2_norm_per_channel = np.sum(
          w.d**2, axis=tuple(shape), keepdims=True
      )
      mask = l2_norm_per_channel > self._pruning_threshold
  
      scope = self.get_parameter_scope(w)
      w_pruned, b_pruned = None, None
      with nn.parameter_scope(scope):
          w_data = w.d * mask
          w_pruned = get_parameter_or_create(
              "w-pruned", w.shape, w_data, True, True
          )
          if b is not None:
              b_data = b.d * mask.reshape((-1,))
              b_pruned = get_parameter_or_create(
                  "b-pruned", b_data.shape, b_data, True, True
              )
      h = self._fct_set[f.info.type_name](
          x, w_pruned, b_pruned, **f.info.args
      )
      return h
  
file_path: nnabla/python/src/nnabla/experimental/graph_converters/prune.py
imports: import nnabla.functions
  import nnabla
  from nnabla.parameter import get_parameter_or_create
  from .graph_converter import FunctionModifier
  import numpy
label_desc: Use image node_id 3 for calling the PruningModifier obj's underlying member method code with example usage: obj.modify(f, inputs) and returns: h